1. Field of the Invention
The present invention relates to an ultrasonic medical system, and more particularly to an ultrasonic medical system for detecting a target tissue through transmission and reception of ultrasound, and computing information regarding the position of the detected target tissue.
2. Description of Related Art
Ultrasonic diagnostic apparatuses are actively utilized in medical diagnosis and treatment. Medical methods which use an ultrasonic diagnostic apparatus so as to specify the position of a tissue to be treated include, as one example, radiation treatment involving irradiation of cancerous tumors.
In radiation treatment, intense radiation is applied to cancerous tissue to kill the tissue. Because it is desirable to minimize irradiation of normal tissue when performing such a radiation treatment, it is important that the position of a tumor tissue be precisely ascertained so as to focus the radiation accurately to the tumor tissue. In order to ascertain the tumor position, image diagnosis by means of radiography, CT (Computed Tomography), or MRI (Magnetic Resonance Imaging) is performed prior to the radiation treatment, so that the position of a tumor tissue is ascertained in advance for determining the position or range for irradiation. With such a method, however, accurate irradiation of a tumor tissue cannot be performed if the position of tumor tissue is moved due to, for example, shifting of the patient""s position or the influence of breathing.
In order to overcome the above disadvantage, a radiation treatment in which the position of a tissue is ascertained using an ultrasonic diagnostic apparatus is also proposed. More specifically, in this method, radiation is directed toward a tumor tissue as the position of the tissue is being detected by an ultrasonic diagnostic apparatus. For example, Japanese Patent Laid-Open Publication No. Hei 8-24263 discloses an apparatus which uses an ultrasonic image for shock wave irradiation.
However, the above method also suffers from a problem. Specifically, since conventional ultrasonic diagnostic apparatuses obtain information regarding a tissue position using an ultrasonic probe as a reference, it may be difficult to obtain appropriate information regarding the position of the tissue, depending on the conditions in which the ultrasonic probe is used. For example, in a case wherein a doctor or other health professional holds an ultrasonic probe in their hand so as to detect a movement of a tumor tissue on a display screen of the ultrasonic diagnostic apparatus, it is not possible to determine whether detected movement is caused by a shift of the tumor tissue itself, or by a shift of the ultrasonic probe while the tumor remains still, or by combination of such movement.
Because information regarding the tissue position obtained by conventional ultrasonic diagnostic apparatuses is based on the ultrasonic probe which functions as a reference as described above, information regarding the position of a target tissue depends on the position of the ultrasonic probe.
It is therefore an advantage of the present invention to provide an ultrasonic medical system capable of outputting appropriate information regarding the tissue position.
The present invention was conceived in view of the aforementioned problems of the related art and provides an ultrasonic medical system comprising a wave transceiver for transmitting and receiving ultrasound with regard to a space including a target tissue and outputting a reception wave signal; first relative coordinate operation means for computing first relative coordinate information of the target tissue using the wave transceiver as an origin, based on the reception wave signal; second relative coordinate operation means for computing second relative coordinate information of the wave transceiver using a reference position as an origin; and combined relative coordinate operation means for computing combined relative coordinate information of the target tissue using the reference position as an origin, based on the first relative coordinate information and the second relative coordinate information, and outputting the combined relative coordinate information.
With the above configuration, because the coordinate information of the target tissue can be obtained using a desired reference position as an origin, the coordinates of the target tissue can be specified independently of the coordinates of the wave transmitter/receiver. For example, even when the wave transceiver moves or when the coordinates of the wave transceiver is not specified, the coordinates of the target tissue can be ascertained as relative coordinates with regard to the known reference position. In the above configuration, each of the first relative coordinate information and the second relative coordinate information may be synthesized information regarding a plurality of coordinate systems. For example, the second relative coordinate information may be coordinate information obtained by synthesis of the second (first) relative coordinate information and the second (second) relative coordinate information. Thus, it is possible to compute the combined relative coordinate information from three or more items of coordinate information including the third relative coordinate information, the fourth relative coordinate information, and the like, based on the same principle as used for computing the combined relative coordinate information from the first and second relative coordinate information.
Preferably, the wave transceiver transmits and receives ultrasound with regard to a three dimensional space including the target tissue, and each of the first relative coordinate information, the second relative coordinate information, and the combined relative coordinate information is three dimensional relative coordinate information. More preferably, the second relative coordinate information includes position information and direction information of the wave transceiver using the reference position as an origin.
Preferably, the above ultrasonic medical system further includes a generator which is provided at either one of a measurement origin whose positional relationship with the reference position is known and the wave transceiver, for generating a measurement signal, and a detector which is provided at the other of the measurement origin and the wave transceiver, for detecting the measurement signal, and the second relative coordinate operation means computes the second relative coordinate information of the wave transceiver using the reference position as an origin, based on the detection result by the detector. With such a configuration in which a non-contact coordinate detection configuration is achieved by the generator and the detector, the movement of the wave transceiver is not limited during coordinate detection. It should be noted that the measurement signal is a signal used for measuring the coordinates of, for example, the position of the wave transceiver. Preferably, the generator is a magnetic field generator for generating a magnetic field, and the detector is a magnetic field detector for detecting the magnetic field. With this configuration, because the magnetic field can be detected by the magnetic field detector without being blocked by a human body, it is possible to maintain the accuracy in computing the coordinates of the wave transceiver irrespective of the body position of a doctor or an examiner. Further, because magnetic fields and ultrasound do not interact with each other, influence of the magnetic field generated by the magnetic field generator on the ultrasound by the wave transceiver, or influence of the ultrasound on the magnetic fields can be disregarded.
Preferably, the first relative coordinate operation means computes the first coordinate information of the target tissue using the wave transceiver as an origin, based on coordinate information specified by an examiner by using an ultrasonic image formed based on the reception wave signal.
Preferably, the above ultrasonic medical system further comprises a holder mechanism for holding the wave transceiver and a measurement information operation unit for outputting measurement information regarding the wave transceiver which is held by the holder mechanism, and the second relative coordinate operation means computes the second relative coordinate information of the wave transceiver using the reference position as an origin, based on the measurement information. More preferably, the measurement information is coordinate information of the wave transceiver relative to a measurement origin whose positional relationship with the reference position is known. Still more preferably, the holder mechanism is an articulated robot, and the measurement information is information based on length data and angle data regarding each movable section of the articulated robot. Further preferably, the wave transceiver is brought into contact with a body surface of a patient, and the holder mechanism includes a pressure sensor for measuring a contact pressure exerted to the patient by the wave transceiver, for controlling the contact pressure to a predetermined value based on the output from the pressure sensor.
Preferably, the above ultrasonic medical system comprises a radiation source apparatus for performing irradiation with radiation while controlling an aim based on the combined relative coordinate information. With this configuration, it is possible to apply radiation intensely to the target tissue, while minimizing irradiation of tissues other than the target tissue by controlling an aim such that radiation is accurately applied to the target tissue. Therefore, the tumor can be killed while irradiation of normal tissues is reduced. As radiation, electromagnetic radiation such as X-rays and gamma-rays, and particle beams such as proton beams and deuteron beams may be used.
Preferably, the radiation source apparatus controls the aim in accordance with a movement of the target tissue based on the combined relative coordinate information. With this configuration, even when, or even as, the target tissue moves, it is possible to apply radiation intensively to the target tissue while minimizing irradiation of tissues other than the target tissue, by controlling the aim such that radiation is accurately applied to the target tissue. Therefore, the tumor can be killed while irradiation of normal tissues is reduced.
The above ultrasonic medical system may further comprise a puncture apparatus for controlling a puncture position based on the combined relative coordinate information. With such a configuration, it is possible to cause a puncture needle to reach the target tissue accurately, by introducing the puncture needle while controlling an aim such that the puncture is focused on the target tissue.
Further, in accordance with another aspect of the present invention, there is provided an ultrasonic medical system comprising an ultrasonic probe which is held by a probe holder mechanism for outputting position and direction information and is brought into contact with a body surface of a patient, the ultrasonic probe transmitting/receiving ultrasound with regard to a three dimensional space including a target tissue; an ultrasonic diagnostic apparatus for obtaining, via the ultrasonic probe, echo data for each of voxels forming the three dimensional space; and a host controller which extracts a voxel corresponding to the target tissue based on an echo level of the echo data, computes first relative coordinate information of the target tissue using the ultrasonic probe as an origin, computes second relative coordinate information of the ultrasonic probe using a reference position as an origin based on the position and direction information, and computes combined relative coordinate information of the target tissue using the reference position as an origin based on the first relative coordinate information and the second relative coordinate information and outputs the combined relative coordinate information.
Preferably, the above ultrasonic medical system further comprises a remedial beam source apparatus for performing irradiation with a remedial beam while controlling an aim in accordance with a movement of the target tissue based on the combined relative coordinate information.